How is thrombotic risk managed in patients with bioprosthetic (artificial tissue) valves?

Management of Thrombotic Risk in Bioprosthetic Valves

For patients with bioprosthetic valves, aspirin 75-100 mg daily is recommended as standard antithrombotic therapy after the initial postoperative period, with vitamin K antagonist (VKA) anticoagulation recommended for the first 3-6 months after valve implantation to reduce thrombotic risk. 1

Initial Antithrombotic Management After Bioprosthetic Valve Implantation

Surgical Bioprosthetic Aortic Valve Replacement

• VKA anticoagulation with an INR goal of 2.5 (range 2.0-3.0) is reasonable for at least 3 months and up to 6 months after surgical bioprosthetic aortic valve replacement 1
• A large Danish registry demonstrated lower risk of stroke and death with VKA therapy extending up to 6 months after bioprosthetic AVR without significantly increased bleeding risk 1
• After the initial 3-6 month period, lifelong aspirin 75-100 mg daily is recommended for patients without other indications for anticoagulation 1

Surgical Bioprosthetic Mitral Valve Replacement

• VKA anticoagulation with an INR goal of 2.5 (range 2.0-3.0) is suggested for the first 3 months after bioprosthetic mitral valve replacement 1
• Patients with bioprosthetic mitral valves have a higher rate of thromboembolism than those with aortic prostheses (2.4% per patient-year versus 1.9% per patient-year) 1
• After the initial anticoagulation period, aspirin 75-100 mg daily is reasonable for long-term therapy 1

Transcatheter Aortic Valve Implantation (TAVI)

• For patients with bioprosthetic TAVI who are at low risk of bleeding, dual-antiplatelet therapy with aspirin 75-100 mg and clopidogrel 75 mg may be reasonable for 3-6 months after valve implantation 1
• Alternatively, VKA anticoagulation with an INR goal of 2.5 may be reasonable for at least 3 months after TAVI 1
• Treatment with low-dose rivaroxaban (10 mg daily) plus aspirin is contraindicated for TAVI patients without other indications for oral anticoagulants 1

Management of Thromboembolic Events with Bioprosthetic Valves

• In patients with bioprosthetic valves who experience a stroke or systemic embolic event while on antiplatelet therapy, VKA anticoagulation may be considered after assessment of bleeding risk 1
• When evaluating thromboembolic events, it's important to rule out infective endocarditis, new-onset atrial fibrillation, and consider whether an underlying hypercoagulable state might be contributing 1
• Leaflet thrombosis occurs more frequently with bioprosthetic transcatheter aortic valves than with bioprosthetic surgical aortic valves 1

Diagnosis and Management of Bioprosthetic Valve Thrombosis

• Transthoracic echocardiography (TTE) is indicated as the first step in evaluation of suspected prosthetic valve thrombosis to assess hemodynamic severity 1
• Transesophageal echocardiography (TEE) is more sensitive for detection of valve thrombosis, especially of mitral prosthetic valves 1
• Four-dimensional computed tomography is becoming the gold standard to directly visualize thrombus on bioprosthetic valves 2
• For confirmed bioprosthetic valve thrombosis, anticoagulation with a VKA is the primary treatment approach 2

Special Considerations

• The risk of major bleeding is increased when antiplatelet agents are added to oral anticoagulants (OR: 1.58,95% CI: 1.14 to 2.18) 3
• Lower daily doses of aspirin (<100 mg) may be associated with lower major bleeding risk than higher doses 3
• Direct oral anticoagulants (DOACs) have not been well-studied for bioprosthetic valve thrombosis and may not provide adequate protection, as evidenced by case reports of valve thrombosis occurring despite DOAC therapy 4
• For patients with both mechanical and bioprosthetic valves, antithrombotic management should follow the more stringent recommendations for mechanical valves 1

Pitfalls and Caveats

• Inadequate anticoagulation in the early postoperative period (first 3-6 months) may increase risk of valve thrombosis and thromboembolic events 1
• Subclinical bioprosthetic valve leaflet thrombosis can occur after surgical valve replacement and may not be detected by standard echocardiography 1
• When transitioning from VKA to antiplatelet therapy after the initial postoperative period, ensure adequate overlap to prevent thrombotic complications 1
• Regular monitoring of valve function with echocardiography is essential to detect early signs of valve thrombosis or dysfunction 1